1. Field of the Invention
The present invention relates to a membrane switch, and in particular to a switch that uses membranes to control whether circuits are on or off and can be applied to, for example, a button switch of any electronic product.
2. Description of Related Art
Membrane switches have been applied widely to key switches of many different electronic products, most notably, keyboards. Each key switch usually includes a key cap and a membrane switch under the key cap. When the key cap is depressed, the membrane switch is conducted to send out a signal.
Reference is made to FIG. 7. A membrane switch 9 of prior art is composed of three membranes, a bottom layer 91, a spacing layer 92, and a top layer 93. The bottom layer 91 is printed with a first conductive trace 912 on its top surface. The top layer 93 is printed with a second conductive trace 932 on its bottom surface. The spacing layer 92 is disposed between the bottom layer 91 and the top layer 93, and is formed with an opening 920. Therefore, the first conductive trace 912 can conduct along with the second conductive trace 932. The disadvantage of this prior art is that three membranes are needed, as can be seen, for example, in U.S. Pat. No. 6,600,121. In particular, the spacing layer 92 is vital to the overall design and does not fulfill industrial and popular trends towards environmental protection.
Reference is made to FIG. 8, in which another membrane switch 8 of prior art is shown. The membrane switch 8 is composed of two membranes, a bottom layer 81 and a top layer 82. The bottom layer 81 is printed with a first conductive trace 812 on its top surface and has a plurality of spacers 814. The spacers 814 are disposed around the first conductive trace 812. The top layer 82 is printed with a second conductive trace 822 at its bottom surface corresponding to the first conductive trace 812. The spacers 814 are used to produce a space between the bottom layer 81 and the top layer 82. This prior art has the disadvantage of needing the spacers 814 which increases costs.
Accordingly, the present invention aims to propose a membrane switch that solves the above-mentioned problems in the prior art.